The use and need for AGC techniques in receivers utilized in satellite communication systems in order to compensate for variations in the power level of the received signal is well known in the art. Generally speaking, the AGC portion of the receiver functions to maintain the power level of the received/incoming signal within some predetermined range.
Typically, satellite receivers utilizing current technology employ digital demodulators which function to downconvert and demodulate the incoming data signal, and which utilize A/D converters to convert the incoming analog data into a digital format. In operation, such A/D converters included in the demodulator require a fixed number of bits so as to provide the necessary resolution so as to allow the carrier recovery loops contained in the demodulator to function properly (e.g., minimize signal quantization errors). The number of bits the A/D requires to provide the necessary resolution can be readily determined based on system requirements. The remaining bits of the A/D converter are utilized to compensate for variations in the power level of the incoming data signal (i.e., the dynamic range of the input data signal). Accordingly, if the input signal is expected to have a large dynamic range, then additional bits of the A/D must be dedicated to handling the variations in the dynamic range.
In prior art systems, when additional bits were necessary to compensate for an increase in the dynamic range of the input signal, the solution was simply to increase the number of bits of the A/D converter. As such, the A/D converter would have the requisite bits necessary to provide the desired resolution, as well as the requisite bits necessary to handle the dynamic range requirements.
However, as the data rates utilized by today's communication systems continue to increase, especially so with satellite communication systems, adding additional bits to the A/D converter to handle an increase in dynamic range is no longer a feasible solution. For example, in a system allocating 5 bits of the A/D converter for signal quantization resolution, and which requires the ability to compensate for a 30 db dynamic range variation with respect to the input signal, an additional 5 bits are necessary. Thus, a 10 bit A/D converter would be required. However, such high resolution A/D converters operating at high data rates (e.g., 800 MHz) would be exceedingly expensive, and clearly could not be utilized in any commercially viable product/system.
Accordingly, there exists a need for an AGC technique and implementation that allows for the compensation of a large dynamic range with respect to the input signal without requiring an increase in the resolution capabilities of the A/D converter contained in the demodulator of the communication system.